Stem brush and method for making same



March 17, 1964 v. K. CHARVAT 3,124,823

STEM BRUSH AND METHOD FOR MAKING SAME Filed April 19, 1961 FIG IWWII/WMQMl/MI FIG2 F|G3 INVENTOR.

VERNON K. CHARVAT 0111mm, a/Donndly ATTORNEYS United States Patent3,124,823 STEM BRUSH AND METHOD FOR MAKING SAME Vernon K. Charvat, BayVillage, Ohio, assignor to The Osborn Manufacturing Company, Cleveland,Ohio, a corporation of Ohio Filed Apr. 19, 1961, Ser. No. 104,152 21Claims. (Cl. -206) This invention relates as indicated to a brushingtool, and more particularly to a brush having a generally helicallyarranged layer of brush material secured between two twisted wire stemmembers. Brushes of this type are frequently employed for the cleaningof boiler tubes and the like and are often known as tube brushes.

In the usual twisted stem brush utilizing wire brush bristle materialclamped between the twisted stem members, the harsh treatment to whichthe brush is subjected generally causes premature failure of the brushlong be fore such brush is actually worn out. Due to the localizedregion in which the wire bristles are gripped, such bristles aresubjected to concentrations of stress in use which result in longfracture of the bristles and consequent deterioration and destruction ofthe brush while the bristle ends have been subjected to relativelylittle wear. Vibration of the fill wires also causes migration of thelatter with consequent occurrence of local voids resulting in unevenbrushing action and eventual loosening and escape of some of thebristles. In Peterson Patent 2,895,155, there is disclosed an improvedwire stern brush construction which represents a substantial improvementover the prior art, and the present invention may be considered afurther improvement on such Peterson disclosure. More particularly, Ibond the layer of bristle material to the supporting stem members in anovel manner to prevent shifting of the latter and also flexiblyresiliently to reinforce such bristles in a gradual manner so that thesupporting effect is gradually reduced outwardly toward the working endsof the bristles; in consequence, there is no localized region ofattachment of the bristles where working stresses may be concentratedand the bristles are not subject to abrupt bending in any such localregion.

It is accordingly an object of this invention to provide a wire stembrush in which the bristles are firmly secured and supported in a mannerto avoid localized flexing of the same.

Another object is to provide such brush, and particularly twisted stembrush in which the bristles may be arranged and secured in a single row.

A. further object is to provide such brush in which the stern wires areadhered together in a manner to prevent their spreading apart in use.

Still another object is to provide such brush in which such stem wiresare secured together in a manner to prevent such wires from shiftinglaterally relative to one another.

A still further object is to provide such brush having much increasedworking life and improved brushing efficiency.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description and the annexeddrawing setting forth in detail certain illustrative embodiments of theinvention, these being indicative, however, of but a few of the variousways in which the principle of the invention may be employed.

In said annexed drawing:

FIG. 1 is a side elevational view of a twisted stern brush in accordancewith this invention but showing different amounts of supporting materialfor the brush bristles in longitudinally spaced regions;

FIG. 2 is a -fragmentary transverse section on an enlarged scale throughsuch twisted stem brush taken on the line 22 on FIG. 1; and

FIG. 3 is a similar transverse section of a modification utilizinghalf-round stem wires and a thicker layer of brush bristle material.

Referring now more particularly to such drawing, the embodiment of theinvention shown in FIG. 1 may comprise two stem wires 1 and 2 having alayer of bristles 3 interposed therebetween, such stem wires beingtwisted tightly together as shown to grip the brush material and disposethe latter in a generally helical layer. The stem wires will ordinarilybe steel wire although other materials such as brass, stainless steeland aluminum wire, for example, may be utilized as desired. Likewise,the brush material employed will ordinarily be steel wire eitherstraight or crimped, but may be other metallic wire, or plasticfilaments such as nylon.

For purposes of illustration, several different forms of the inventionhave been shown in the single FIG. 1 of the drawing although it will beappreciated that ordinarily.

the entire length of any individual brush will be uniform in accordancewith one or another of the embodiments described below. Thus, at theextreme left end of FIG. 1 as viewed in the drawing, the brush bristlematerial 3 is shown gripped between the twisted stern members 1 and 2 inconventional manner without provision of the special bristle supportingmaterial of this invention. As shown at 4, however, such stem wires maybe bonded together by an adhesive elastomeric material which alsoextends -a short distance outwardly along the bristles to reinforce thelatter. In the regions successively indicated by the numerals 5, 6, '7and 8, the stem wires are similarly bonded together and the supportingmaterial extends progressively greater distances radially outwardly ofthe layer of brush material, filling the space between the latter, andin the region denoted by the numeral 8, the outer working bristle endsprotrude only a relatively short distance beyond such supportingmaterial.

.As better shown in FIG. 2 of the drawing, such supporting material 9,which may, for example, preferably be an elastomeric material such aspolyurethane, is shown bonding the stem wires 1 and 2 together and alsoextending a relatively short distance approximately equal to thediameter of an individual stem wire outwardly in each direction alongthe bristles 3 which are gripped between such wires. By thus bonding thestem wires together, the latter are substantially prevented fromspringing Iapart as they may otherwise tend to do following the twistingoperation, the wires being mechanically held tightly twisted until thestrongly adherent polyurethane resin has set. Such resin likewise servesto prevent spreading apart of the stem wires when the tool is placed inuse and thereby ensures that the layer of brush bristles remains firmlygripped and will not be loosened and shed in use. Therehas in the pastalso frequently been a tendency for the twisted stem wires to shiftlaterally of one another so that they are no longer directly opposed toone another in the most effective position to grip the brush bristlelayer, and this undesired action is similarly prevented by the bondingmedium 9. Furthermore, such bonding medium extends an appreciabledistance longitudinally outwardly along the brush bristles to affordprogressively diminishing support for the latter while at the same timebonding such bristles to the stem wires themselves. In consequence, thebristles are resiliently supported adjacent the region where they aregripped by the stem wires in a manner preventing longitudinalconcentrations of stress in the bristles when the brush is placed inuse, regardless of whether such use involves axial reciprocation of thebrush or rotation about the axis of the central support, or acombination of such actions. In effect, due to the gradually diminishingthickness of the bristle supporting medium 9 outwardly along thebristles, a gradually uniformly diminishing degree of flexure ispermitted to such bristles radially inwardly toward the central supportand there is no localized point or region where the bristles tend to besharply flexed when the brush is placed in use.

A generally similar situation prevails in the regions indicated at 6, 7and 8 on FIG. 1 except that the elastomeric bonding material, whichbonds strongly both to the stem wires and the brush material, extendsoutwardly a substantially greater distance with the outer end portionsof the bristles projecting a shorter distance therebeyond and with theelastomeric bonding material completely enclosing and protecting thecentral twisted stem wire members 1 and 2. The brush bristlesaccordingly are capable of a stronger or harsher brushing action but arestill supported in the general manner described above in that suchsupporting material extends outwardly along each layer of bristles in amanner to support the latter to a gradually diminishing extent so thatthere is no sudden or abrupt release of the bristles thereby which wouldtend to promote sharply localized bending of the bristles in use.

Now referring more specifically in FIG. 3, the embodiment of theinvention there illustrated is generally similar to that shown in FIG. 2but half round stem wires 16 and D1 are employed to grip the layer ofbrush bristle material 12 between their opposed fiat faces, therebyaffording a more secure clamping action on the latter. While the layerof brush bristle material 12 is shown as being several bristles inthickness, it will be understood that this form of construction may beutilized when clamping but a single row of bristles therebetween (as inFIG. 2), and that, equally, the FIG. 2 embodiment may likewise beutilized when clamping a layer of bristles of greater thickness thanillustrated. The elastomeric material 13 serves to bond the twisted stemwires 10 and 11 together and also to bond the bristles 12 together andto such stem wires in the same general manner as in the FIG. 2embodiment.

As will be noted from an inspection of FIGS. 2 and 3, the elastomericmaterial may desirably assume a meniscus shape in the region betweeneach stem wire and the layer of brush material to achieve the graduallydiminishing flexible support for such brush material which it is anobject of this invention to obtain. In some cases, and particularly whenthe elastomeric bristle supporting material extends a substantialdistance radially outwardly of the tool as shown at 6, 7 and 8 in FIG.1, it is desirable that such elastomeric supporting material be ofcellular structure having a multitude of small cells therein, the termcellular being employed to include both structures where the cellsintercommunicate with one another and where such cells are entirelyseparated from one another by intervening webs. Foamed polyurethane hasbeen found satisfactory inasmuch as it has a high heat distortion point,good flexibility, tensile and compressive strength, good adhesiveproperties, and may be applied in liquid form without the necessity ofemploying molds to produce the desired meniscus mentioned above.Inasmuch as the outer working portions of the bristles protrudeappreciably beyond the body of the supporting material, unnecessaryrubbing of such supporting material against the work being brushed isavoided which would otherwise tend to generate undesirable heat.

In a sense, it appears that the elastomeric supporting material as shownin FIG. 2, for example, acts like wedges interposed between the layer ofbrush fill material and the stem wires 1 and 2, with the additionalfactor that these elastomeric wedges are adhered both to the stem wiresand the fill material and accordingly act in tension as well as incompression. As long as the stem wires are not permitted to shiftrelative to one another, the brushing load will not be transmitted tosuch wires in any multiplying manner as does occur when such stem wiresmove apart and a moment arm is provided. Once the stem wires movesomewhat apart, the forces tending to separate them in use become verymuch larger.

While polyurethane is ordinarily much preferred as the bonding andsupporting medium, other elastomeric materials such as neoprene(polychloroprene), polyurethane rubber, and vinyl resins may be utilizedin a similar manner. Liquid or semi-liquid resins which will form thedesired meniscus will usually be selected, and such liquid resins whichare capable of rapid gelling are desirable. The stem wires and bristlewires may be treated with an appropriate primer such as an epoxy resinto enhance the bonding effect of the resiliently deformable elastomericmaterial. The liquid resin is placed on the brush and the latter rotatedslowly (e.g. 25-35 r.p.m.) about its axis while the resin gells. Theoperation is facilitated if such resin is one having a fairly highsurface tension.

In a typical preferred example, the bristles may be carbon steel wirehaving a diameter of .0O2.0l0 inch and a Knoop hardness in excess of600, the elastomeric material being polyurethane. The stem wires neednot necessarily be twisted together but may instead extend closelyparallel to one another as shown in Peterson Patent 2,465,396, forexample, with the brush material forming a straight flat layer. Flatfaced stern wires as shown in FIG. 3 are especially suitable for use inthis manner. As taught herein, relatively small amounts of resilientlydeformable elastomeric material employed in a strategic location, ofproper shape, and bonded to the bristles, serve greatly to extend theregion where the principal bristle bending takes place and henceincreases the serviceable life of the brushing tool.

In another example, a brushing tool in accordance with this inventionwas produced utilizing .8 grams of fill Wire, and a twisted wire stem 7inches in length, the brush being /1. inch in diameter and having abrush face 1 /2 inches long. The brush was heated to about 200 F. beforeapplying a heated polyurethane rubber composition and then rotated at25-35 r.p.m. until such composition gelled. After complete gellation,the brush was baked in an oven at 212 F. for two hours.

Other modes of applying the principle of the invention may be employed,change being made as regards the de tails described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I therefore particularly point out and distinctly claim as my invention:

1. A twisted wire stem brush comprising two stem wires twisted togetherwith brush material clamped therebetween, and elastomeric materialstrongly adhesively bonded both to said stem wires and to said brushmaterial effective to retain said stem wires in close direct oppositionto one another for continued tight gripping of said brush material andalso effective to prevent shifting of said brush material, saidelastomeric material penetrating said brush material to effect a directconnection between said respective stem wires.

2. The brush of claim 1, wherein said stem wires have opposed fiatfaces.

3. The brush of claim 1, wherein said brush material is steel wire.

4. The brush of claim 1, wherein said brush material comprises a singlerow of parallel wire bristles.

5. The brush of claim 1, wherein said elastomeric material ispolyurethane.

6. The brush of claim 1, wherein said elastomeric material is foamedpolyurethane.

7. The brush of claim 1, wherein said elastomeric material extends onlya portion of the length of said brush material outwardly from said stemwires and is of gradually diminishing thickness to afford progressivelyless support for such brush material toward the outer working ends ofthe latter.

8. A twisted wire stem brush comprising two stem wires twisted togetherwith brush material clamped therebetween, and elastomeric materialbonded both to said stem wires and to said brush material andpenetrating the latter effective directly to retain said stem wires inclose direct opposition to one another for continued tight gripping ofsaid brush material and also efiective to prevent shifting of said brushmaterial, said elastomeric material extending only a portion of thelength of said brush material outwardly from said stem wires and beingof gradually diminishing thickness to afiord progressively less supportfor said brush material toward the outer working ends of the latter,said elastomeric material having a general meniscus surface contourbetween said stem wires and the exposed outer portions of said brushmaterial.

9. The brush of claim 8, wherein said elastomeric material ispolyurethane.

10. The brush of claim 8, wherein said elastomeric material is a foamedelastomer.

11. The brush of claim 8, wherein said brush material is straight Wirebristles.

12. In a brush comprising two stem members and a fiat layer of brushmaterial held therebetween, strong adhesive bonding material embeddingsaid brush material in the region of said stern members and alsoadhesively bonding said two stem members directly together to preventseparation of the latter.

13. The brush of claim 12, wherein said bonding material is anelastomeric material.

14. The brush of claim 12, wherein said bonding material ispolyurethane.

15. The brush of claim 12, wherein said bonding material is foamedpolyurethane.

16. In a brush comprising two stem members and a flat layer of brushmaterial held therebetween, elasto meric material adhesively bondeddirectly to both said stem members and to said brush material eifectiveto re tain said stem members in close direct opposition to one anotherfor continued tight engagement with said brush material and alsoeffective to prevent shifting of said brush material.

17. The brush of claim 16, wherein said elastomeric material extendsonly a portion of the length of said brush material outwardly from saidstem members and is of gradually diminishing thickness to affordprogressively less support for said brush material toward the outerworking ends of the latter.

18. In a twisted wire stem brush having two stem wires twisted togetherand a helical generally flat layer of brush material clampedtherebetween, elastomeric material interposed between the helical turnsof brush material and embedding the inner portions of the latteradjacent said stem wires, said elastomeric material being adhesivelybonded to said stem'wires and all said brush material and being ofgradually diminishing thickness outwardly toward the working ends ofsaid brush material to afford progressively diminishing support for saidbrush material toward such outer ends.

19. The brush of claim 18, wherein said elastomeric material completelyfills the space between such helical turns of brush material in theregion adjacent said stem wires.

20. The method of producing a brushing tool which comprises securingspaced layers of brush bristle material to a central support with suchbristles extending generally radially outwardly from the latter,applying a rapid gelling liquid elastomeric resin to such assembledbrush in contact with such support, and then rotating such brush aboutthe longitudinal axis of such support uniformly circumferentially todistribute such resin while the resin gels to meniscus conformation oneach side of each such layer of bristle material.

21. A brushing tool comprising a central support and spaced layers ofbrush material secured thereto and extending generally radiallyoutwardly therefrom, and elastomeric material bonded to said bristlesand also to said support intermediate said layers, said elastomericmaterial being formed in general meniscus shape so that it extendsoutwardly along such layers in gradually diminishing thickness whilestill bonded thereto.

References Cited in the file of this patent UNITED STATES PATENTS2,190,206 Churchill Feb. 13, 1940 2,634,167 Bible Apr. 7, 1953 2,895,155Peterson July 21, 1959 2,950,495 Stingly Aug. 30, 1960 2,995,401Peterson Aug. 8, 1961 FOREIGN PATENTS 409,462 Great Britain May 3, 1934827,928 Great Britain Feb. 10, 1960

12. IN A BRUSH COMPRISING TWO STEM MEMBERS AND A FLAT LAYER OF BRUSHMATERIAL HELD THEREBETWEEN, STRONG ADHESIVE BONDING MATERIAL EMBEDDINGSAID BRUSH MATERIAL IN THE REGION OF SAID STEM MEMBERS AND ALSOADHESIVELY BONDING SAID TWO STEM MEMBERS DIRECTLY TOGETHER TO PREVENTSEPARATION, OF THE LATTER